With the proliferation of personal computing devices such as desktop/laptop computers, personal digital assistants (PDAs), smartphones, tablets, and the like, many users have adopted cloud storage services to access their data across the various computing devices they use/own. Generally speaking, a cloud storage service enables a user to upload files to a cloud storage server for centralized storage in a remote storage location (i.e., in “the cloud”). Once the service has stored the files in the cloud, the user can download/synchronize the files from the cloud storage server to local storage on each of the user's computing devices.
Some cloud storage services automatically synchronize data between the cloud storage server and a user's computing devices in a manner that causes each computing device to maintain, in local storage, a complete and up-to-date copy of each of the user's cloud-stored files. In this configuration (referred to as a “fully synced” configuration), the user always has local access to the latest versions of his/her files, from every computing device participating in the synchronization arrangement.
Other cloud storage services allow a user to download cloud-stored files to his/her computing devices on-demand. In this configuration (referred to as an “on-demand” configuration), a particular computing device only downloads a file from the cloud storage server to local storage when the user explicitly requests the file via that device. The computing device can then cache the downloaded file locally for future access (until, e.g., a newer version of the file becomes available on the cloud storage server).
The two approaches above have different advantages and disadvantages, and thus neither is an ideal solution for accessing cloud-stored data. With the fully synced configuration, a user will typically not experience any network delay when trying to access cloud-stored files on his/her computing devices because the user's computing devices store synchronized copies of the files locally. Further, the user can access the files while offline. However, the locally stored files can potentially consume a large amount of local storage space on each computing device. The on-demand configuration minimizes consumption of local storage space since a computing device only downloads files from the cloud storage server that a user explicitly requests. However, the user may experience significant latency at the time of accessing a file due to the download process, particularly if the network connection between the computing device and the cloud storage server is slow or if the file is large.